Buying guide for best dial calipers
Carpenters have a saying, “Measure twice; cut once.” This is true whether you’re cutting a piece of granite for a kitchen countertop or checking the brake pads on a customer’s car. Precision measurements are a requirement in today’s world, which means you need tools that will give you accurate readings each and every time you use them. The finer the tolerances, the more accurate they need to be. Welcome to the world of dial calipers.
Calipers aren’t new. They have been around since the Han Dynasty in China, but it was Frenchman Pierre Vernier who invented the “graduated” caliper in 1631. In 1851, American businessman Joseph R. Brown began to mass produce them. Today, dial calipers are standardized and widely available.
Many dial calipers appear virtually identical, so it can often be difficult to figure out which ones are best and which are a waste of time.
Key considerations
Measuring limit
The first thing you need to consider is the size of the items you’ll be measuring. Most people find that a 6-inch measuring limit on the beam (the long arm of the caliper) is sufficient for their needs. However, if you need to measure something larger than 6 inches, extended dial calipers are available, but they are much more expensive.
Maintenance
Tools get dirty. It’s a fact of life. But “dirty” is a relative term. What an auto mechanic would consider acceptable, an office technician might deem filthy. The dirtier the environment you work in, the more scrupulous you’ll have to be about keeping your caliper clean in order to prevent it from seizing up. Calipers require absolute cleanliness in order to function properly, so if you work in an area where there’s a lot of grime, stock up on cleaning supplies (see below).
Features
Material
Stainless steel is the usual material used to make dial calipers. However, some manufacturers go the extra step of applying a titanium nitride (TiN) coating to the sliding surface to increase the resistance to wear. It adds a bit to the price, but it extends the life of the tool, too
Case
If you drop your dial caliper or hit it against something, it can be knocked out of alignment and require recalibration. If it can’t be recalibrated, you’ve lost an expensive tool. Make sure your dial caliper comes with a case that has a custom-molded foam interior to hold the tool firmly in place. If it can bounce around in the case, the caliper could get damaged.
Fractional vs. decimal
Fractional: Come caliper dials are marked in fractions (1/3, 5/16, 1/8, and so on). This is only a problem if the needle falls between two lines. You’ll have to convert the fractions to decimals then estimate the distance between the marks and figure accordingly. There’s nothing inherently wrong with that method, but If that’s not your cup of tea, check the numbers on the dial caliper before buying instead of assuming you know what they are.
Decimal: Dial calipers with decimal readings are easier to work with. When you read the numbers on the dial, read the line closest to the left edge of the needle, also known as the reference line. Divide the distance between the two marks into tenths and gauge it accordingly. Since the numbers are already in decimals, you don’t need to convert anything.
English vs. metric
Unfortunately, Americans need two sets of tools: one in English measurements of inches and pounds, and another in metric measurements of millimeters and grams. It’s decidedly inconvenient, but that’s the way it is. The result is that you might have to get two dial calipers, one for each type of measuring system. However, there are some dial calipers that have both scales on the dial. If you have to use both sets of tools during the day, a dual-scale model might be your best bet.
Accessories
Cleaning solvent: CCS Methyl Alcohol
When you need to clean your caliper, use pure methyl alcohol. It cleans the gears and teeth on the caliper and evaporates without leaving any residue. This 32-ounce bottle from CCS should last a long while.
Compressed air: Office Depot Cleaning Duster
Tools get dirty, and dial calipers are no exception. Use this compressed air from Office Depot to blow out all the dirt and grit from the teeth and gears. You get three 10-ounce cans for a reasonable price.
Tool oil: 3-IN-ONE Multi-Purpose Oil
After you’ve finished cleaning your dial caliper, give it a light coating of oil to keep everything moving smoothly. This oil from 3-IN-ONE comes in a handy 8-ounce squeeze bottle for more control over how much you use.
Dial caliper prices
Inexpensive: The low price range for dial calipers is $15 to $33. The main things you’ll notice with these models are substandard cases and lesser quality.
Mid-range: The medium price range is from around $34 to $100. The tolerances on these calipers are better, and the carrying cases are generally well made. However, some of these can be damaged from even minor drops and impacts.
Expensive: Over $100 is where you’ll find the best-quality calipers, including extended calipers.
Tips
- Check the caliper occasionally. When the large jaws are closed, you shouldn’t be able to see any daylight between them. No light means the dial caliper is in good condition and you can use it. If you can see light between the jaws, the caliper needs to be cleaned and then rechecked.
- Calibrate your calipers before using them. Loosen the bezel nut on the bottom of the dial, then twist the dial until the needle is at zero. Tighten the bezel nut and you’re ready to go.
FAQ
Q. Can I use WD-40 to clean my dial caliper?
A. No. WD-40 leaves a film that will gunk up the gears and teeth. Use a light machine or tool oil instead.
Q. How do I measure with a dial caliper?
A. Loosen the lock screw on the upper side of the caliper with the short jaws. If you’re measuring the inside of a pipe or getting some other internal measurement, use the short jaws. If you’re measuring the external width of an object, such a piece of wood or a metal handle, use the large external jaws. roll the round thumb screw on the side of the caliper where the large jaws are located to open and close the jaws until they are firmly set against the object you’re measuring. Tighten the upper lock screw and your measurement is complete. Now you’re ready to take a reading.
Q. How do I read a dial caliper?
A. The mobile jaw is the reference edge where you take the large reading on the caliper. Read the line to the left of the reference edge. Now look at the dial. For example, if the large reading is between 3 and 4, you’re now going to get the difference between them from the dial. The reading on the dial is normally measured at 0.001. If the dial reads 20, that would be 0.020 so the total measurement in our example would be 3.020. Depending on the caliper, it would be inches or centimeters.
